Concrete Foundation

Foundation walls can be built using concrete block, Insulated
Concrete Forms (ICFs), or most commonly poured concrete. With
a crew of helpers to move blocks and mix mortar, an experienced
block mason can erect a simple crawl space foundation wall in just a
couple days. However, in many parts of the country, poured
concrete foundations have surpassed concrete block walls in popularity.
Concrete foundation subcontractors can be hired to form and pour concrete
walls and that's exactly what we did on our cabin. If a
concrete foundation contractor arrives in the morning with a truckload of
wall forms and rebar, he will probably have everything erected
before the end of the day. Don't forget to have the forms
inspected before the concrete truck arrives to fill them with
concrete.

Concrete foundation forms are usually stripped a day or two after the pour. It
takes about a week for concrete to get its first hard set, but you
can begin to lay out and install the sills as soon as the forms come
off. Even though you may not be forming and pouring the walls
yourself, it's useful to know about some aspects of the process.
This applies to whether you're building foundation walls with
concrete block or with insulated concrete forms.

The concrete foundation work was one of the few items we hired out on our
cabin project.
Since we didn't have access to the forms and other equipment for
pouring forms we elected to have someone else do the work.
We had the sub bill the concrete to us directly and we provided the
window bucks for the concrete foundation. Here's some pictures of the
final product since we were not around to see it actually take
place.

Concrete Foundation Insulation

Concrete foundation insulation isn't used in mild climates. In areas
with frigid winter months it can improve interior comfort and save
on heating costs. Even though it's not required by code in
many areas, it's definitely worth installing wherever prolonged
freezing temperatures are expected. You can install insulation
on the inside or outside of a crawl space or basement wall.
Exterior insulation, in the form of rigid foam boards, is glued to
the foundation walls before backfilling. Where they're exposed
above the finished grade on the exterior, insulation boards must be
protected with siding material or stucco. It's important to
remember that any type of foundation insulation can provide a hidden
passageway for termites and other insects to enter the house.
Make sure you cut off this passageway by installing a termite shield
beneath the sill. The picture below shows an example of rigid
foam insulation installed on the exterior of the concrete foundation wall.

Concrete
Foundation for Cabin

The concrete foundation work was one of the few items we hired out.
Since we didn't have access to the forms and other equipment for
pouring forms we elected to have someone else do the work.
We had the sub bill the concrete to us directly and we provided the
window bucks for the foundation. Here's some pictures of the
final product since we were not around to see it actually take
place.

The concrete foundation is 8' tall and 8" thick except for the drop-down
in the front were the foundation is 10' tall.

Foundation
Anchor Bolts and Tie-Downs

Regardless of the type of foundation, anchor bolts are required
around the perimeter to hold the sill plates and the walls securely
in place. The picture below shows these bolts inserted in the
top of the concrete foundation. In earthquake and hurricane zones, the building code
may call for additional hold-downs, such as metal straps (a.k.a.
hurricane straps) that are embedded or bolted to the foundation and
extended to the sills, rim joists, and wall framing. Most
codes require that a long piece of rebar be planted in the concrete
near the planned location of the main electrical panel so that it
can be used as a ground for the electrical system. The is
known as an ufer ground (see footing section which shows the ufer
ground tied into the footing rebar).

Concrete
Foundation Coatings

It's important to keep moisture out of your basement or crawl space
area, as well as out of the masonry wall itself. Foundation
coatings help accomplish this. Concrete block walls are often
parged (covered with a layer of mortar that conceals and protects
the joints between the blocks). A waterproof coating should
also be applied. Asphalt-type coatings are popular because
they are inexpensive and have been used for many years. More
effective and expensive coatings are also available and should be
considered when you're building in soil that stays wet for extended
periods of time. No matter how good a waterproof coating is
supposed to be, it shouldn't be your only line of defense against
under-house moisture.

For our cabin foundation, we picked up some foundation tar at Home
Depot and rolled a thick layer on the concrete foundation that would be below
grade. See picture below.

Backfill around the Concrete Foundation

The foundation is ready for the floor framing work to begin but the
job site isn't. Backfilling against the walls restores at
least of the site's original contour, making it safer and easier to
move around. If you're building a house with a full basement,
the backfilling process is sometimes delayed until after the first
floor is framed and sheathed because they are taller and basement
walls need the extra rigidity provided by the floor framing to
ensure that backfilling doesn't damage the foundation. The
isn't a major concern with crawl spaces.

Ensuring Proper Foundation Drainage

Follow the guidelines below and you'll stand a pretty good chance of
keeping water on the outside of your foundation:

Don't build on the lowest part of the lot

Seal all holes around the pipes that go through the concrete

Install perforated drainpipes at the bottom of the concrete
footings around the outside of the foundation

Coat the foundation walls with a suitable damp-proofing or
water-proofing treatment. Check with builders in your area
or the local building department to find out which foundation
coatings are recommended. Tar coatings are inexpensive but
not as effective as more recently developed waterproofing
treatments.

Compact loose fill as you backfill around the foundation,
but be careful, because excessive compaction can damage masonry
walls. Make sure the finish grade (ground level) slopes
away from the foundation. Remember that loose fill can
settle. A finished grade that slopes away from the house
may later slope toward the house should settling occur.

Use gutters and downspouts to manage high roof water runoff.
Make sure you keep gutters unclogged and install downspouts to
direct water away from the house.

Cabin Foundation Drain

We put a foundation drain around the perimeter of the cabin to
take care of any drainage problems that might exist. We
followed the advice on ensuring proper drainage given the fact we had a
major irrigation canal running directly behind our lot not more that
40ft from our cabin. We used 4" perforated black drain pipe
for this drain. We also picked up a stretchable sock made just
for this application that goes over the drain pipe to prevent
sediment and debris from getting into the drain. Luckily we
had just enough slope on our lot to run the ends of the drain to the
end of the lot and be OK. Without this, we would have needed
to run to a sump pump.